22 November 2013

Controlling blood pressure, cholesterol, and blood glucose may
reduce the risk of heart disease and stroke associated with being
overweight or obese.

A pooled analysis of 97 prospective studies from around the
world found that the increased risk of heart disease or stroke in
overweight and obese people is partly because their weight
increases their chances of having high blood pressure, high
cholesterol and high blood glucose.

The study, by a worldwide research consortium led by a team from
the Harvard School of Public Health, Imperial College London, and
the University of Sydney, covered a total of 1.8 million
participants.

Worldwide, obesity has nearly doubled since 1980, according to a
previous study by the research team, and more than 1.4 billion
adults aged 20 and older are overweight or obese. Being overweight
increases one's risk of heart disease and stroke - the leading
causes of death worldwide - diabetes, and several types of cancer.
The researchers had also previously estimated that 3.4 million
annual deaths are due to excess weight.

There has been debate over whether excess weight causes heart
disease and stroke through effects on other risk factors,
particularly blood pressure, cholesterol, and glucose, and whether
treatments that address these factors can offset the risks of being
overweight.

The study found that high blood pressure, serum cholesterol, and
blood glucose explain up to half of the increased risk of heart
disease and three quarters of the increased risk of stroke among
overweight or obese people. High blood pressure poses the biggest
risk of the three metabolic factors examined, accounting for 31 per
cent of the increased risk of heart disease and 65 per cent of the
increased risk of stroke.

"Our results show that the harmful effects of being overweight
or obese on heart disease and stroke partly occur by increasing
blood pressure, serum cholesterol and blood glucose. Therefore, if
we control these risk factors, for example through better diagnosis
and treatment of hypertension, we can prevent some of the harmful
effects of being overweight or obese," said Goodarz Danaei of the
Havard School of Public Health.

Professor Majid Ezzati from Imperial College London said:
"Controlling hypertension, cholesterol, and diabetes through
medication is useful, but not enough to offset the harms of
overweight and obesity. So we need to need to find creative
approaches that can curb and reverse the global obesity
epidemic."

Professor Stephen Hill, Chair of the Medical Research Council's
Molecular and Cellular Medicine Board, which part-funded the work,
said: "Large, long-term population studies like this one are a very
powerful tool, allowing researchers to disentangle individual
factors and understand how they each contribute to our risk of
disease. It's interesting that, even when blood pressure, blood
sugar and cholesterol are brought under control, obese individuals
are still at a higher risk of heart attack and stroke. This
suggests that other factors might be at play, which is likely to be
of interest for future research into the consequences of
obesity."

A worldwide analysis of 97 studies involving a total of
1.8 million participants has shown that controlling blood pressure,
cholesterol, and blood glucose may reduce the risk of heart disease
and stroke associated with being overweight or
obese.

Globally, obesity has nearly doubled since 1980 and
affects more than 1.4 billion people aged 20 and over. Being
overweight increases the risk of heart disease, stroke diabetes,
and several types of cancer, with 3.4 million deaths a year
attributed to excess weight.

Funding for the study came from the Medical Research
Council; the National Institute for Health Research Imperial
Biomedical Research Centre; the US National Institutes of Health;
the Lown Scholars in Residence Program on cardiovascular disease
prevention; and from a Harvard Global Health Institute Doctoral
Research Grant.

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